6 V batteries & A Link to Good DC Systems Primer

[Roc]

Hi folks,
Stopped by Sam's Club (not a member, but wanted to check out batteries), looking for Trojan batteries.  Looks like they don't carry them, and the brand they have is Engergizer.  Every size they have is the Engergizer brand.  Sticker says 'Dist. by Johnson Controls Battery Group'.  The 6vold golf cart battery is model EGC2.  Reserve capacity says '105' (could this be a Trojan 105 twin?).  Amp hours is 220.  Cost is $71.28.  Certainly not the $40 something price as years past, but still not bad.  Wondering if anyone has information on these batteries.

Thanks!

[Jon Schneider]

They are mysterious.  All I can tell you is that I bought four of them last year, and they've been fine so far, but a year's worth of light duty is hardly much of a test.  I'll let you know in five years or so if I'm still satisfied with them

[Rick Johnson]

I'd agree with Jon.  Installed mine about 1 1/2 years ago and still very happy, but they don't get much of a workout here on the lake...

Cheers,

Rick

[Jim Moore]

I have had mine now going into it's fifth season with no problems, also using a xantrex 20 amp charger. Maybe this year, whether they need it or not, I think I will replace them just to be on the safe side since they aren't extremely costly.  For me, it has been a great value.

[Lance Jones]

I know that the threads on 6v are plenty. What are the primary advantages to them vs 12v and I have 2 banks of series 27 12v, how many 6v would replace them?

[Jon Schneider]

I know that the threads on 6v are plenty. What are the primary advantages to them vs 12v and I have 2 banks of series 27 12v, how many 6v would replace them?

The only way to answer that would be to know how many AH each of those banks offers.  Two golf-cart-sized 6V batteries typically deliver between 200 and 250AH at 12V.  The ones we're talking about deliver 220AH, but know that you always have to pair 6V batteries in order to gross them up to 12V.  The advantage is that they tend to be longer-lasting and more durable (but brand quality is a factor here) and usually offer more power per square inch of floor space due at least in part to the fact that they tend to be taller than their 12V brothers.  In the case of at least the Mk I, they provide a way to really maximize the amount AH in the starboard aft-most settee where most of us have most of our house power supply.  I have 440AH coming out of that space with four 6V batteries.  That would not be possible with Group 24/27/31 batteries, because the most you could fit in that space would be three, and those batteries tend not to deliver more that 120AH.  It did occur to me recently that four Optima 12V batteries might fit in there (haven't confirmed this), which would actually deliver 480AH in that space, albeit at a higher price/AH.

[Lance Jones]

I know I should read the threads; but, I learn better by asking questions. I take it you wire the 6v in series? Also, could I replace one bank w/6v and leave the other 12v until I get the replacement 6v? Yes, price is an issue?

[Jon Schneider]

I take it you wire the 6v in series? Also, could I replace one bank w/6v and leave the other 12v until I get the replacement 6v? Yes, price is an issue?

Yes, in series, and there's no problem combining a 12V bank composed of 12V batteries with another 12V bank composed of 6V batteries in serial.  Price may be an issue.  If you buy a Group 27 deep cycle flooded cell 80AH battery from WM, you'll pay $1.50/AH ($120 for the battery).  If you buy two Energizer 6V flooded cells from Sam's Club, you'll pay .65/AH ($145 for the pair).  You could definitely get a cheaper deep cycle battery than one from WM, but that was easy for me to look up. You could also get a much more expensive 6V battery, which could invert the value equation.  In fact, if you buy WM 6V batteries, you'd be paying $1.77/AH, so perhaps that's a fairer comparison.

[Lance Jones]

Good answer!!!! One other question. I have added the WM batter accessory terminals so I simply clip in my bilge pump and solar charger to the appropriate +/- terminal. With it being in serial, would I put the + on one end of the series and the - on the other end?

[Jon Schneider]

I have added the WM batter accessory terminals so I simply clip in my bilge pump and solar charger to the appropriate +/- terminal. With it being in serial, would I put the + on one end of the series and the - on the other end?

That's exactly right, although I've never been able to rationalize in my head why it matters, since the whole grid is 12V.  Guess that it's theoretically a better flow of electrons. 

[Lance Jones]

Or do I jsut pick two posts on the same battery?

[Stu Jackson]

Lance,

STOP for a second, and think about the 6V batteries you have now connected into a 12V "bank" you have created.  If you connect to the 12V positives you're fine, if you connect to the 6V positive intermediate points it won't work (or at half speed).  Just connect to the + on the 12V sides of the BANKS, not the interconnecting wiring between the 6V batteries.

And, dare I suggest doing a wiring diagram if you haven't already?  That'll almost answer your question, and a good thing to have for future reference.

[Lance Jones]

Stop? I didn't even know I was moving. So, you say on 6v battery 1 place a +/-terminal and then on 6v battery 2 place the opposite terminal for accessories?

[Stu Jackson]

Another good primer I stumbled upon, in addition to this (scroll to the top to start the thread): http://www.catalina-capri-25s.org/forum/topic.asp?whichpage=0.52&TOPIC_ID=19250#144657  is this (from the same C25 MB discussion):  http://www.ccis.com/home/mnemeth/12volt/12volt.htm.  It includes this picture of the difference between 12V and 6V wiring, which you already have installed.  Scroll down on this link for a picture of more than two batteries connected in a bank.

So, forget about the 6V side of things, and simply concentrate on the 12V end of the system.  Like, forget you have wired (2) 6V batteries together, and just use the end posts of the 12V "bank."  Eliminate any confusion that way, keep it simple.  Use the lower right and upper left posts of the 12V bank shown in the right hand 6V wiring diagram [6 volt wiring diagram] below.

Lance, you can start movin' again now! 

[Lance Jones]

  Nothing clearer than a picture!